This invention relates to an improved corner member which is particularly adapted for use with freight containers and more specifically with containerized cargo containers. This corner member provides the container with the means which allow the container to be lifted or coupled to other containers or secured to surfaces such as ships deck, the floor of a railroad car or the ground.
Such containers are commonly in use for hauling freight by ship, rail or air wherein the shipping container itself could form the body portion of a vehicle or the means for holding and stacking material being hauled within vehicles.
A system for handling, securing and lifting such containers is discussed in U.S. Pat. No. 3,042,227. This patent discloses apparatus for transferring freight containers of the type referred to herein into the hold of a ship for transportation to a desired location. In such a transfer system, a crane or other suitable lifting mechanism is lowered into position over the cargo container and is removably coupled to the container. Thereafter, the container can be lifted or transferred as is necessary.
The disclosed mechanism for removably coupling the lifting mechanism to the container consists of at least a pair of twist lugs which are attached to the lifting mechanism and which fit into suitably designed sockets located in the container. However, the patent contains no disclosure as to the design of that portion of the container which receives the twist lug. In practice, however, containers of the type referred to in U.S. Pat. No. 3,042,227 have one key slot type opening in the top face of the container at each corner into which twist lugs fit.
When constructed in this fashion, the container, while being liftable by twist lug elements, cannot be easily lifted by a conventional lifting hook nor can containers be easily coupled vertically or horizontally.
An example of a socketed corner member designed for containers is disclosed in U.S. Pat. No. 2,963,310, a substantially rectangular recess which opens through the upper face of the corner member via a generally rectangular opening of a size suitable to receive a twist lug.
Several different embodiments are shown in U.S. Pat. No. 2,963,310 and each of the corners is fitted with a similar corner member having only one hole in the upper wall for the top corners or one hole in the bottom wall for the bottom corners. The container could be picked up, secured to the ground or a deck or secured to a container either directly above or directly below. No coupling, however, can be effected from a horizontal direction and requires the use of separate spacing devices such as vertical spacer beams.
More recently, containers of the type referred to herein have been provided with corner members which would allow for both vertical and horizontal coupling. However, such corner members have suffered from the problem that one corner member would not fit on each corner of the container and provide the essential coupling requirements. Thus, at least two separately designed corner member elements would have to be used in order to provide the proper lifting and/or coupling means. This required that each type of corner member be inventoried and that the proper corner member for the respective corner be used during assembly of the container since use of the wrong corner would make that particular section of the container unusable.